Retro-cutting instrument with adjustable limit setting

ABSTRACT

Cutting instruments and related methods are disclosed herein in which the diameter of the retrograde cutting blade can be adjusted to any of a plurality of diameter settings, allowing the same instrument to be used to form holes of different diameters. The limit diameter can be preset such that, during the cutting operation, the user need not be concerned with selecting the appropriate diameter, but rather can simply deploy the cutting blade until the preset limit is reached. Cutting instruments are also disclosed in which the retrograde cutting blade is distinct from the forward drilling tip and protected within a cavity formed in the body of the instrument when not in use, as are instruments in which the user is given visual and/or tactile feedback to confirm desired positioning of the cutting blade.

FIELD

Retro-cutting instruments and related methods are disclosed herein.

BACKGROUND

During arthroscopic surgery, a small incision is made in the skincovering the arthroscopic site or joint so that surgical instruments maybe placed in the joint and manipulated through arthroscopicvisualization. The surgical instruments can be used to perform varioustasks, such as forming a recipient site socket (e.g., a femoral ortibial bone tunnel) for receiving a soft tissue graft duringreconstructive surgery.

For example, in a typical trans-tibial arthroscopic ACL procedure, adrill is used to form recipient site sockets in the tibia and the femur.The drill is first used to form a tunnel through the tibia, starting atthe anterior surface of the tibia and advancing inward towards the kneejoint. The resulting tibial tunnel provides access to the femur fordrilling a femoral tunnel, starting within the joint space and advancingtowards the exterior of the femur. Drilling of the femoral tunnel ceaseswhen the desired depth is reached, such that the resulting femoraltunnel is a blind hole, with only a small guide wire sized holeextending all the way through to the exterior of the femur. In thistrans-tibial approach, the femoral tunnel is more or less straight upand down, which is biomechanically suboptimal and reduces the rotationalstability of the joint.

One way to improve joint biomechanics and rotational stability is toinstead use an anteromedial portal in the femur. In an anteromedialapproach, a drill is inserted through a portal formed in the front ofthe knee on the medial side into the femoral notch to drill a tunnel inthe lateral condyle. The resulting bone tunnel is placed in a moreanatomically-correct position. This approach involves severalchallenges, however, that arise from limitations of existing cuttinginstruments. For example, the surgeon must be careful when advancing therelatively large-diameter drill to avoid damaging the cartilage of themedial condyle.

An alternative method is to use an outside-in approach with aretro-cutting instrument to form a stepped opening in the femur, asshown in FIG. 1. Initially, a hole having a diameter D1 is drilled,starting at the outside of the femur and advancing inward towards thejoint in the direction of the illustrated arrow A1. The drill is thenpartially withdrawn in the direction of the illustrated arrow A2 with aretro-cutting feature activated to widen a distal portion of the hole toa diameter D2. The retro-cutting feature is then de-activated to allowthe drill to be completely withdrawn through the reduced-diameterproximal portion of the hole. There are many other procedures in whichit can be desirable to form a stepped opening in a similar manner.

Existing retro-cutting instruments suffer from a number ofdisadvantages. For example, existing instruments can only retro-cuttunnels of a single diameter. Thus, when a need exists to drill multipletunnels with different diameters, multiple instruments having differentdiameters must be used, increasing inventory and sterilization costs aswell as surgical complexity.

Furthermore, in existing retro-cutting instruments, the drill tip forforward cutting and the retrograde cutting tip are one in the same. Whenretrograde cutting is to be performed, the forward cutting tip is simplyhinged outward such that it is disposed approximately perpendicular tothe main drill shaft. In this position, the open end of the main drillshaft tends to spread open and the tip can break off. Also, since thesame structure is used to perform forward drilling and retrogradecutting, the shape of the structure cannot be optimized for one task orthe other. This can reduce the instrument's cutting performance and/orincrease the risk of the tip being damaged.

Accordingly, a need exists for improved cutting instruments and relatedmethods.

SUMMARY

Cutting instruments and related methods are disclosed herein in whichthe diameter of the retrograde cutting blade can be adjusted to any of aplurality of diameter settings, allowing the same instrument to be usedto form holes of different diameters. The limit diameter can be presetsuch that, during the cutting operation, the user need not be concernedwith selecting the appropriate diameter, but rather can simply deploythe cutting blade until the preset limit is reached. Cutting instrumentsare also disclosed in which the retrograde cutting blade is distinctfrom the forward drilling tip and protected within a cavity formed inthe body of the instrument when not in use, as are instruments in whichthe user is given visual and/or tactile feedback to confirm desiredpositioning of the cutting blade.

In some embodiments, a cutting instrument includes an elongate bodyhaving proximal and distal ends, the distal end defining a drilling tip,a cutting blade pivotally disposed within a cavity formed in theelongate body such that the cutting blade is positionable in a retractedposition in which the cutting blade does not protrude from the elongatebody and one or more deployed positions in which the cutting bladeprotrudes from the elongate body, an actuation shaft extending throughthe elongate body and having a distal end coupled to the cutting bladesuch that longitudinal translation of the actuation shaft relative tothe elongate body is effective to move the cutting blade between theretracted position and the one or more deployed positions, an actuationknob coupled to the actuation shaft such that rotation of the actuationknob about a longitudinal axis of the elongate body is effective tolongitudinally translate the actuation shaft relative to the elongatebody, and an adjustment element configured to limit the degree to whichthe actuation shaft can be longitudinally translated relative to theelongate body based on a position of the adjustment element relative tothe elongate body.

The cavity in which the cutting blade is disposed can be spaced adistance apart from the distal end of the elongate body. The actuationknob can be coupled to the actuation shaft by a threaded interface. Theactuation shaft can include a first tab that extends through a firstslot in the elongate body. The adjustment element can be disposed overat least a portion of the first slot to limit the degree to which thefirst tab can slide within the first slot. The adjustment element caninclude a ring having a stepped stop surface formed thereon, the steppedstop surface having a plurality of steps. Rotation of the adjustmentelement about the longitudinal axis of the elongate body can beeffective to change which of the plurality of steps is aligned with thefirst slot and thereby change an effective length of the first slot. Theinstrument can include a fixed handle portion having a plurality ofprotrusions formed thereon configured to be received within a pluralityof detents or openings formed in a distal-facing surface of theadjustment element. The instrument can include a bias spring configuredto urge the adjustment element into engagement with the fixed handleportion. The actuation knob can include a torque limiter configured tolimit the amount of torque which can be applied in rotating theactuation knob and configured to provide tactile feedback to a user whenthe cutting blade has reached a desired position. The distal end of theactuation shaft can be coupled to the cutting blade by a linkagemechanism. The linkage mechanism can include a link bar having aproximal end coupled to a yoke of the actuation shaft by a first crosspin and a distal end coupled to a yoke of the cutting blade by a secondcross pin. Proximal translation of the actuation shaft relative to theelongate body can be effective to rotate the cutting blade about a pivotpin to retract the cutting blade into the cavity and distal translationof the actuation shaft relative to the elongate body can be effective torotate the cutting blade about the pivot pin to deploy the cutting bladefrom the cavity.

In some embodiments, a cutting instrument includes an elongate bodyhaving a distal drilling tip, and a cutting blade selectively deployablefrom a cavity formed in the elongate body at a location proximal to thedistal drilling tip, the cutting blade being deployable to any of aplurality of diameters.

In some embodiments, a method of cutting bone comprises drilling a firstopening in the bone having a first diameter using a distal tip of acutting instrument, a cutting blade of the cutting instrument beingretracted into a body of the cutting instrument during said drilling;after drilling the first opening, deploying the cutting blade such thatthe cutting blade at least partially protrudes from the body of thecutting instrument; and, after deploying the cutting blade, cutting asecond opening in the bone having a second diameter which is larger thanthe first diameter using the cutting blade of the cutting instrument.

The first and second openings can be contiguous with one another suchthat the first and second openings define a stepped bone tunnel. Thefirst opening can be drilled in an antegrade direction and the secondopening can be cut in a retrograde direction. The first opening can bedrilled in an antegrade direction and the second opening can be cut inan antegrade direction. The first opening can be formed in a tibia andthe second opening can be formed in a femur. The first opening can beformed in a medial portion of a femur and the second opening can beformed in a lateral portion of the femur. The method can include, aftercutting the second opening, retracting the cutting blade into the bodyof the cutting instrument and withdrawing the cutting instrument throughthe first opening. The method can include setting a cutting bladedeployment diameter to one of a plurality of diameter settings of thecutting instrument.

The present invention further provides devices and methods as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be more fully understood from the following detaileddescription taken in conjunction with the accompanying drawings, inwhich:

FIG. 1 is a schematic perspective view of a human knee joint with astepped bone tunnel formed in a femur;

FIG. 2A is a perspective view of an exemplary embodiment of a cuttinginstrument;

FIG. 2B is a sectional profile view of a distal end of the cuttinginstrument of FIG. 2A;

FIG. 2C is an exploded view of the actuation shaft and cutting blade ofthe instrument of FIG. 2A;

FIG. 2D is another exploded view of the actuation shaft and cuttingblade of the instrument of FIG. 2A;

FIG. 2E is a sectional profile view of a proximal end of the cuttinginstrument of FIG. 2A;

FIG. 2F is an exploded view of the proximal end of the cuttinginstrument of FIG. 2A;

FIG. 3A is a perspective view of another exemplary embodiment of acutting instrument;

FIG. 3B is a sectional profile view of a distal end of the cuttinginstrument of FIG. 3A;

FIG. 3C is a sectional profile view of a proximal end of the cuttinginstrument of FIG. 3A;

FIG. 3D is an exploded view of the proximal end of the cuttinginstrument of FIG. 3A;

FIG. 3E is a plan view of a handle portion of the cutting instrument ofFIG. 3A;

FIG. 4A is a perspective view of another exemplary embodiment of acutting instrument;

FIG. 4B is a sectional profile view of a distal end of the cuttinginstrument of FIG. 4A;

FIG. 4C is a sectional profile view of a proximal end of the cuttinginstrument of FIG. 4A;

FIG. 4D is an exploded view of the proximal end of the cuttinginstrument of FIG. 4A;

FIG. 4E is a perspective view of the proximal end of the cuttinginstrument of FIG. 4A shown with an adjustment knob and bias springremoved;

FIG. 4F is an exploded view of an adjustment knob and disc handle of thecutting instrument of FIG. 4A;

FIG. 5A is a perspective view of another exemplary embodiment of acutting instrument;

FIG. 5B is a sectional profile view of a distal end of the cuttinginstrument of FIG. 5A;

FIG. 5C is an exploded view of the distal end of the cutting instrumentof FIG. 5A;

FIG. 5D is a sectional profile view of a proximal end of the cuttinginstrument of FIG. 5A;

FIG. 5E is an exploded view of the proximal end of the cuttinginstrument of FIG. 5A;

FIG. 5F is a perspective view of the proximal end of the cuttinginstrument of FIG. 5A shown with an adjustment knob and bias springremoved;

FIG. 6A is a perspective view of another exemplary embodiment of acutting instrument;

FIG. 6B is an exploded view of a distal end of the cutting instrument ofFIG. 6A;

FIG. 6C is a partially-exploded view of the distal end of the cuttinginstrument of FIG. 6A;

FIG. 6D is a sectional profile view of a proximal end of the cuttinginstrument of FIG. 6A;

FIG. 6E is an exploded view of the proximal end of the cuttinginstrument of FIG. 6A;

FIG. 6F is a perspective view of the proximal end of the cuttinginstrument of FIG. 6A shown with an actuation knob and bias springremoved;

FIG. 7A is a perspective view of another exemplary embodiment of acutting instrument;

FIG. 7B is a partially-exploded view of the distal end of the cuttinginstrument of FIG. 7A;

FIG. 7C is a sectional profile view of a proximal end of the cuttinginstrument of FIG. 7A;

FIG. 7D is an exploded view of the proximal end of the cuttinginstrument of FIG. 7A;

FIG. 7E is a perspective view of a torque limiter and adjustment ring ofthe cutting instrument of FIG. 7A;

FIG. 7F is a perspective view of the actuation knob of the cuttinginstrument of FIG. 7A;

FIG. 7G is a perspective view of the proximal end of the cuttinginstrument of FIG. 7A shown with an actuation knob, bias spring, andforward handle portion removed;

FIGS. 8A, 8B, 8C, 8D, 8E, and 8F illustrate an exemplary method of usinga cutting instrument;

FIGS. 9A, 9B, 9C, 9D, 9E, and 9F illustrate another exemplary method ofusing a cutting instrument; and

FIGS. 10A, 10B, 10C, 10D, 10E, and 10F illustrate another exemplarymethod of using a cutting instrument.

DETAILED DESCRIPTION

Cutting instruments and related methods are disclosed herein in whichthe diameter of the retrograde cutting blade can be adjusted to any of aplurality of diameter settings, allowing the same instrument to be usedto form holes of different diameters. The limit diameter can be presetsuch that, during the cutting operation, the user need not be concernedwith selecting the appropriate diameter, but rather can simply deploythe cutting blade until the preset limit is reached. Cutting instrumentsare also disclosed in which the retrograde cutting blade is distinctfrom the forward drilling tip and protected within a cavity formed inthe body of the instrument when not in use, as are instruments in whichthe user is given visual and/or tactile feedback to confirm desiredpositioning of the cutting blade.

Certain exemplary embodiments will now be described to provide anoverall understanding of the principles of the structure, function,manufacture, and use of the devices and methods disclosed herein. One ormore examples of these embodiments are illustrated in the accompanyingdrawings. Those of skilled in the art will understand that the devicesand methods specifically described herein and illustrated in theaccompanying drawings are non-limiting exemplary embodiments and thatthe scope of the present invention is defined solely by the claims. Thefeatures illustrated or described in connection with one exemplaryembodiment may be combined with the features of other embodiments. Suchmodifications and variations are intended to be included within thescope of the present invention. In the present disclosure, like-numberedcomponents of the embodiments generally have similar features and/orpurposes.

FIGS. 2A-2F illustrate an exemplary embodiment of a cutting instrument200.

As shown, the instrument 200 generally includes an elongate body 202that extends from a proximal end 202 p to a distal end 202 d along alongitudinal axis L. The instrument 200 also includes an actuation shaft204, a cutting blade 206, an actuation knob 208 having an inner tube210, a washer 212, and a retaining clip 214.

The proximal end of the body 202 defines a faceted mating interface orshank 216 for coupling to the chuck of a drill (e.g., an electric orpneumatic surgical drill). The distal end of the body defines asharpened tip 218 for cutting a hole in an object in an antegrade orforward direction. The tip 218 can have any of a variety of shapes orconfigurations, and can be optimized for forward cutting performance.The body 202 also includes a cavity 220 in which the cutting blade ispivotally mounted via a cross pin 222. The cutting blade 206 can beselectively deployed or retracted through the opening of the cavity 220.In other words, the cutting blade 206 can be positioned in a deployedconfiguration, as shown in FIG. 2B, in which the blade protrudes throughthe opening, and a retracted configuration in which the blade does notprotrude through the opening. The degree to which the blade 206protrudes from the opening can be adjusted to adjust the diameter of thehole that is formed when the instrument 200 is used in a cuttingoperation. The cutting blade 206 can have any of a variety of shapes orconfigurations, and can be optimized for retrograde cutting and/orantegrade cutting performance.

The actuation shaft 204 extends through an inner lumen of the body 202and is longitudinally-translatable relative to the body. The distal endof the actuation shaft 204 can be coupled to the cutting blade 206 inany of a variety of ways. For example, as shown in FIGS. 2B-2D, thedistal end of the actuation shaft 204 defines a bayonet-shaped tip thatis coupled to the cutting blade 206. In particular, the proximal end ofthe cutting blade 206 defines a yoke in which the distal end of theactuation shaft 204 is received. A male projection 224 formed on theinterior of the yoke defines a curved camming surface that engages acorresponding curved camming surface of a female receptacle 226 formedin the tip of the actuation shaft 204. In operation, proximaltranslation of the actuation shaft 204 relative to the body 202 causesthe blade 206 to pivot about the cross pin 222 and to be deployedthrough the opening. The degree to which the actuation shaft 204 istranslated proximally controls the degree to which the cutting blade 206protrudes from the opening. Distal translation of the actuation shaft204 relative to the body 202 causes the blade 206 to pivot in theopposite direction about the cross pin 222 and to be retracted into thecavity.

As shown in FIGS. 2E-2F, a cylindrical proximal portion of the bodydefines a first longitudinal slot 228 in which a first tab portion 230of the actuation shaft 204 is slidably positioned. The slot 228 has alength that is greater than the length of the tab 230, such that the tabcan slide longitudinally within the slot between a proximal position inwhich the blade 206 is fully-deployed and a distal position in which theblade is fully-retracted. The length of the slot 228 thus defines therange of diameters to which the blade 206 can be deployed and thereforethe range of tunnel diameters that can be formed by the blade.

The cylindrical proximal portion of the body 202 also defines a secondlongitudinal slot 232 in which a second tab portion 234 of the actuationshaft 204 is slidably positioned. The inner tube 210 of the actuationknob 208 is rotatably positioned over the cylindrical proximal portionof the body 202 such that a threaded interior surface 236 of the innertube engages a threaded surface of the second tab 234 of the actuationshaft 204. The actuation knob 208 is positioned over the inner tube 210such that the inner tube sits within a distal cylindrical recess formedin the actuation knob. A hexagonal male portion of the inner tube 210engages a hexagonal female portion of the actuation knob 208 to fix therotational position of the actuation knob relative to the inner tube.The washer 212 is disposed in a proximal cylindrical recess formed inthe actuation knob 208 and held in place by a retaining clip 214 thatsnaps into a slot 238 formed in the exterior surface of the body 202.The actuation knob 208 is sandwiched between the retaining clip 214 anda shoulder 240 formed on the body 202 to maintain the actuation knob ata fixed longitudinal position relative to the body. Accordingly,rotation of the actuation knob 208 (and the inner tube 210 coupledthereto) relative to the body 202 causes the threads of the actuationshaft 204 to ride along the threads of the inner tube, thus causing theactuation shaft to translate longitudinally relative to the body. Theproximal and distal limits of this longitudinal translation are definedby the size of the first slot 228 relative to the first tab 230 formedon the actuation shaft 204. The actuation knob 208 can be rotated in afirst direction about the longitudinal axis L to pull the actuationshaft 204 proximally and deploy the blade 206 and/or increase thecutting diameter. The actuation knob 208 can also be rotated in asecond, opposite direction about the longitudinal axis L to push theactuation shaft 204 distally and retract the blade 206 and/or decreasethe cutting diameter.

While a threaded interface for advancing and retracting the actuationshaft 204 is shown, it will be appreciated that various other mechanismscan be used instead or in addition. In some embodiments, the threadedinterface advantageously provides increased mechanical advantage formoving the cutting blade 206, which can prevent the cutting blade fromgetting stuck in the deployed or retracted positions during a cuttingoperation. In addition, while a rotatable actuation knob is shown anddescribed herein, it will be appreciated that any of a variety ofactuation mechanisms can be used instead or in addition, includingbuttons, levers, triggers, and so forth.

In an exemplary method of using the instrument 200, the instrument canbe prepared for use by coupling the instrument to a drill and rotatingthe actuation handle 208 to position the blade 206 in thefully-retracted position. When the surgeon is ready to form a steppedopening, the surgeon actuates the drill to form the reduced diameterportion of the opening with the forward cutting tip 218. The surgeonthen rotates the actuation handle 208 until further rotation is notpossible, indicating that the blade 206 has been deployed. The surgeonthen actuates the drill to retro-cut the enlarged diameter portion ofthe stepped opening. Finally, the surgeon rotates the actuation handle208 to return the cutting blade 206 to the fully-retracted position andwithdraws the instrument 200 from the patient. The instrument 200 canalso be used in other exemplary methods, as described further below.

FIGS. 3A-3E illustrate another exemplary embodiment of a cuttinginstrument 300.

As shown, the instrument 300 generally includes an elongate body 302that extends from a proximal end 302 p to a distal end 302 d along alongitudinal axis L. The instrument 300 also includes an actuation shaft304, a cutting blade 306, an actuation knob 308, a handle 310, a slideindicator 312, and a retaining clip 314.

The proximal end of the body 302 defines a faceted mating interface orshank 316 for coupling to the chuck of a drill (e.g., an electric orpneumatic surgical drill). The distal end of the body 302 defines asharpened tip 318 for cutting a hole in an object in an antegrade orforward direction. The tip 318 can have any of a variety of shapes orconfigurations, and can be optimized for forward cutting performance.The body 302 also includes a cavity 320 in which the cutting blade 306is pivotally mounted via a cross pin 322. The cutting blade 306 can beselectively deployed or retracted through the opening of the cavity 320.In other words, the cutting blade 306 can be positioned in a deployedconfiguration, as shown in FIG. 3B, in which the blade protrudes throughthe opening, and a retracted configuration in which the blade does notprotrude through the opening. The degree to which the blade 306protrudes from the opening can be adjusted to adjust the diameter of thehole that is formed when the instrument 300 is used in a cuttingoperation. The cutting blade 306 can have any of a variety of shapes orconfigurations, and can be optimized for retrograde cutting and/orantegrade cutting performance.

The actuation shaft 304 extends through an inner lumen of the body 302and is longitudinally-translatable relative to the body. The distal endof the actuation shaft 304 can be coupled to the cutting blade 306 inany of a variety of ways. For example, as shown in FIG. 3B, the distalend of the actuation shaft 304 defines a bayonet-shaped tip that iscoupled to the cutting blade 306 (e.g., in the same manner as discussedabove with respect to the instrument 200). In operation, proximaltranslation of the actuation shaft 304 relative to the body 302 causesthe blade 306 to pivot about the cross pin 322 and to be deployedthrough the opening. The degree to which the actuation shaft 304 istranslated proximally controls the degree to which the cutting blade 306protrudes from the opening. Distal translation of the actuation shaft304 relative to the body 302 causes the blade 306 to pivot in theopposite direction about the cross pin 322 and to be retracted into thecavity 320.

As shown in FIGS. 3C-3D, a cylindrical proximal portion of the body 302defines a first longitudinal slot 328 in which a first tab portion 330of the actuation shaft 304 is slidably positioned. The slot 328 has alength that is greater than the length of the tab 330, such that the tabcan slide longitudinally within the slot between a proximal position inwhich the blade 306 is fully-deployed and a distal position in which theblade is fully-retracted. The length of the slot 328 thus defines therange of diameters to which the blade 306 can be deployed and thereforethe range of tunnel diameters that can be formed by the blade.

The cylindrical proximal portion of the body 302 also defines a secondlongitudinal slot 332 in which a second tab portion 334 of the actuationshaft 304 is slidably positioned. The actuation knob 308 is rotatablypositioned over the cylindrical proximal portion of the body 302 suchthat a threaded interior surface of the actuation knob engages athreaded surface of the second tab 334 of the actuation shaft 304.

The actuation knob 308 is substantially cylindrical and includes a largepitch exterior thread 342 in which a lower portion of the slideindicator 312 is slidably disposed. The actuation knob 308 is receivedwithin the handle 310 such that the actuation knob is rotatable relativeto the handle and such that an upper portion of the slide indicator 312is slidably disposed in a slot 344 formed in the handle. The handle 310and the actuation knob 308 are sandwiched between a proximal retainingclip 314 and a shoulder 340 formed on the body 302 to maintain theactuation knob at a fixed longitudinal position relative to the body.The handle portion 310 can optionally be rotatably fixed relative to thebody 302. In operation, rotation of the actuation knob 308 relative tothe body 302 and the handle portion 310 causes the threads of theactuation shaft 304 to ride along the threads of actuation knob, thuscausing the actuation shaft to translate longitudinally relative to thebody. The proximal and distal limits of this longitudinal translationare defined by the size of the first slot 328 relative to the first tab330 formed on the actuation shaft 304. The actuation knob 308 can berotated in a first direction about the longitudinal axis L to pull theactuation shaft 304 proximally and deploy the blade 306 and/or increasethe cutting diameter. The actuation knob 308 can also be rotated in asecond, opposite direction about the longitudinal axis L to push theactuation shaft 304 distally and retract the blade 306 and/or decreasethe cutting diameter.

The instrument 300 also defines a number of intermediate stop pointsbetween the fully -deployed and the fully-retracted blade positions. Asthe actuation knob 308 rotates, the slide indicator 312 rides in thelarge pitch thread 342. The indicator 312 is captive in the slot 344formed in the handle 310, such that the indicator translateslongitudinally relative to the handle as the actuation knob 308 isrotated. The indicator 312 includes a main protrusion 313 that indicatesthe selected cutting diameter. The indicator 312 also includes a secondprotrusion 315 adjacent to the main protrusion that interfaces with aplurality of lateral branches 346 of the slot 344 as the actuation knob308 is rotated. When the second protrusion 315 clicks into a lateralbranch 346, the user receives tactile feedback that the next diametersetting has been reached. Markings can be printed or otherwise formed onthe handle 310 to provide an indication to the user as to the extent ofblade deployment. In the illustrated embodiment, as shown in FIG. 3E,numerical graduations are included to represent the available cuttingdiameter settings in millimeters (e.g., 3.5 mm diameter in thefully-retracted position and diameters of 6 to 12 mm in one millimeterincrements for the various deployed positions). As also shown in FIG.3E, the lateral slots 346 can define half millimeter increments betweeneach full millimeter setting. It will be appreciated that theseavailable diameters are merely exemplary and, as discussed below, theinstrument 300 can be configured to provide any of a variety ofdiameters or ranges of diameters.

In an exemplary method of using the instrument 300, the instrument canbe prepared for use by coupling the instrument to a drill and rotatingthe actuation handle 308 to position the blade 306 in thefully-retracted position. When the surgeon is ready to form a steppedopening, the surgeon actuates the drill to form the reduced diameterportion of the opening with the forward cutting tip 318. The surgeonthen rotates the actuation knob 308 until the desired hole diameter isindicated by the slide indicator 312 and the handle 310. The surgeonthen actuates the drill to retro-cut the enlarged diameter portion ofthe stepped opening. Finally, the surgeon rotates the actuation knob 308to return the cutting blade 306 to the fully-retracted position andwithdraws the instrument 300 from the patient. The instrument 300 canalso be used in other exemplary methods, as described further below.

FIGS. 4A-4F illustrate another exemplary embodiment of a cuttinginstrument 400.

As shown, the instrument 400 generally includes an elongate body 402that extends from a proximal end 402 p to a distal end 402 d along alongitudinal axis L. The instrument 400 also includes an actuation shaft404, a cutting blade 406, an actuation knob 408, a disc handle 410, astop ring 412, and an adjustment knob 448.

The proximal end of the body 402 defines a faceted mating interface orshank 416 for coupling to the chuck of a drill (e.g., an electric orpneumatic surgical drill). The distal end of the body 402 defines asharpened tip 418 for cutting a hole in an object in an antegrade orforward direction. The tip 418 can have any of a variety of shapes orconfigurations, and can be optimized for forward cutting performance.The body 402 also includes a cavity 420 in which the cutting blade 406is pivotally mounted via a cross pin 422. The cutting blade 406 can beselectively deployed or retracted through the opening of the cavity 420.In other words, the cutting blade 406 can be positioned in a deployedconfiguration, as shown in FIG. 4B, in which the blade protrudes throughthe opening, and a retracted configuration in which the blade does notprotrude through the opening. The degree to which the blade 406protrudes from the opening can be adjusted to adjust the diameter of thehole that is formed when the instrument 400 is used in a cuttingoperation. The cutting blade 406 can have any of a variety of shapes orconfigurations, and can be optimized for retrograde cutting and/orantegrade cutting performance.

The actuation shaft 404 extends through an inner lumen of the body 402and is longitudinally-translatable relative to the body. The distal endof the actuation shaft 404 can be coupled to the cutting blade 406 inany of a variety of ways. For example, as shown in FIG. 4B, the distalend of the actuation shaft 404 defines a bayonet-shaped tip that iscoupled to the cutting blade 406 (e.g., in the same manner as discussedabove with respect to the instrument 200). In operation, proximaltranslation of the actuation shaft 404 relative to the body 402 causesthe blade 406 to pivot about the cross pin 422 and to be deployedthrough the opening. The degree to which the actuation shaft 404 istranslated proximally controls the degree to which the cutting blade 406protrudes from the opening. Distal translation of the actuation shaft404 relative to the body 402 causes the blade 406 to pivot in theopposite direction about the cross pin 422 and to be retracted into thecavity.

As shown in FIGS. 4C-4E, a cylindrical proximal portion of the body 402defines a first longitudinal slot 428 in which a first tab portion 430of the actuation shaft 404 is slidably positioned. The slot 428 has alength that is greater than the length of the tab 430, such that the tabcan slide longitudinally within the slot between a proximal position inwhich the blade 406 is fully-deployed and a distal position in which theblade is fully-retracted. The length of the slot 428 thus defines therange of diameters to which the blade 406 can be deployed and thereforethe range of tunnel diameters that can be formed by the blade. The stopring 412 has a threaded interior surface that is threaded onto athreaded exterior portion 450 of the body 402. As shown in FIG. 4E, thestop ring 412 covers at least a proximal portion of the slot 428, suchthat the proximal travel limit of the tab 430 is defined by the stopring. A cross-pin 452 fixes the rotational position of the adjustmentknob 448 relative to the stop ring 412, such that rotation of theadjustment knob is effective to rotate the stop ring relative to thebody 402. Such rotation causes the stop ring 412 to translatelongitudinally along the body 402. Accordingly, rotating the adjustmentknob 448 in a first direction about the longitudinal axis L advances thestop ring 412 distally to effectively reduce the length of the slot 428and thus decrease the maximum cutting diameter. Rotating the adjustmentknob 448 in a second, opposite direction about the longitudinal axis Lretracts the stop ring 412 proximally to effectively increase the lengthof the slot 428 and thus increase the maximum cutting diameter.

The cylindrical proximal portion of the body 402 also defines a secondlongitudinal slot 432 in which a second tab portion 434 of the actuationshaft 404 is slidably positioned. The actuation knob 408 is rotatablypositioned over the cylindrical proximal portion of the body 402 suchthat a threaded interior surface of an inner tube 454 mounted in theactuation knob engages a threaded surface of the second tab 434 of theactuation shaft 404.

The actuation knob 408 is sandwiched between a proximal retaining clip414, which engages a groove 438 in the body 402, and the disc handle 410to maintain the actuation knob at a fixed longitudinal position relativeto the body 402. In operation, rotation of the actuation knob 408relative to the body 402 and the handle portion 410 causes the threadsof the actuation shaft 404 to ride along the threads of the actuationknob 408, thus causing the actuation shaft to translate longitudinallyrelative to the body. The proximal limit of this longitudinaltranslation is defined by the longitudinal position of the stop ring 412over the first slot 428. The actuation knob 408 can be rotated in afirst direction about the longitudinal axis L to pull the actuationshaft 404 proximally and deploy the blade 406 and/or increase thecutting diameter. The actuation knob 408 can also be rotated in asecond, opposite direction about the longitudinal axis L to push theactuation shaft 404 distally and retract the blade 406 and/or decreasethe cutting diameter.

As noted above, the position of the stop ring 412 can be adjusted byrotating the adjustment knob 448 relative to the body 402 and the dischandle 410. As shown in FIGS. 4D-4F, the adjustment knob 448 includes apin 456 that extends proximally from a proximal-facing end surface ofthe adjustment knob. The pin 456 can be received in any of a pluralityof holes 458 formed in the disc handle 410. Each of the holes 458 isindexed to a predetermined cutting diameter (e.g., such that movement ofthe pin 456 from one hole to an adjacent hole results in a 0.5 mmincrease or decrease in cutting diameter, depending on the direction ofthe adjacency). To adjust the diameter setting, the adjustment knob 448can be urged distally to withdraw the pin 456 from the holes 458 in thedisc handle 410. The adjustment knob 448 can then be rotated to thedesired setting (which can be indicated by markings on the adjustmentknob and an indicator arrow 460 on the disc handle 410). Finally, theadjustment knob 448 can be urged proximally such that the pin 456engages one of the plurality of holes 458 formed in the disc handle 410.A bias spring 462 can be provided to urge the adjustment knob 448 in theproximal direction. When the pin 456 is seated in one of the holes 458,it prevents the adjustment knob 448 from being rotated, and ensures thatthe stop ring 412 will not inadvertently move. This ensures that theinstrument 400 remains set to the desired diameter throughout thecutting operation. The bias spring 462 provides compression on theadjustment knob 448, keeping the pin 456 seated in the hole 458 untilthe user overcomes the spring force by pushing the adjustment knobdistally. A distal c-clip 464 can be attached to the body 402 to providea distal stop for the bias spring 462.

In an exemplary method of using the instrument 400, the instrument canbe prepared for use by a surgical technician on a “back table” beforehanding the instrument to the surgeon or other user. This preparationcan include setting the cutting diameter using the adjustment knob 448as described above and rotating the actuation knob 408 to position theblade 406 in the fully-retracted position. When the surgeon is ready toform a stepped opening, the surgeon actuates a drill to which theinstrument 400 is coupled to form the reduced diameter portion of theopening with the forward cutting tip 418. The surgeon then rotates theactuation knob 408 until further rotation is not possible, indicatingthat the blade 406 has been deployed to the pre-determined limit set bythe surgical technician using the adjustment knob 448. The surgeon thenactuates the drill to retro-cut the enlarged diameter portion of thestepped opening. Finally, the surgeon rotates the actuation handle 408to return the cutting blade 406 to the fully-retracted position andwithdraws the instrument 400 from the patient. Accordingly, the surgeonneed not be concerned with setting the instrument 400 to the desireddiameter while the instrument is in the patient. Rather, the desireddiameter is pre-set and thus the surgeon can simply turn the actuationknob 408 until the stop ring 412 is engaged by the tab 430, reliablyreaching the desired cutting diameter. In other words, the surgeon doesnot need to look at scales or calibrations when deploying the blade 406.The instrument 400 can also be used in other exemplary methods, asdescribed further below.

FIGS. 5A-5F illustrate another exemplary embodiment of a cuttinginstrument 500.

As shown, the instrument 500 generally includes an elongate body 502that extends from a proximal end 502 p to a distal end 502 d along alongitudinal axis L. The instrument 500 also includes an actuation shaft504, a cutting blade 506, an actuation knob 508, a disc handle 510, astop ring 512, and an adjustment knob 548.

The proximal end of the body 502 defines a faceted mating interface orshank 516 for coupling to the chuck of a drill (e.g., an electric orpneumatic surgical drill). The distal end of the body 502 defines asharpened tip 518 for cutting a hole in an object in an antegrade orforward direction. The tip 518 can have any of a variety of shapes orconfigurations, and can be optimized for forward cutting performance.The body 502 also includes a cavity 520 in which the cutting blade 506is pivotally mounted via first and second side pins 522. The cuttingblade 506 can be selectively deployed or retracted through the openingof the cavity 520. In other words, the cutting blade 506 can bepositioned in a deployed configuration, as shown in FIG. 5B, in whichthe blade protrudes through the opening, and a retracted configurationin which the blade does not protrude through the opening. The degree towhich the blade 506 protrudes from the opening can be adjusted to adjustthe diameter of the hole that is formed when the instrument 500 is usedin a cutting operation. The cutting blade 506 can have any of a varietyof shapes or configurations, and can be optimized for retrograde cuttingand/or antegrade cutting performance.

The actuation shaft 504 extends through an inner lumen of the body 502and is longitudinally-translatable relative to the body. The distal endof the actuation shaft 504 can be coupled to the cutting blade 506 inany of a variety of ways. For example, the actuation shaft 504 can becoupled to the cutting blade 506 in the same manner as discussed abovewith respect to the instrument 200. FIGS. 5B-5C, however, illustrate analternative mechanism for coupling the actuation shaft 504 to thecutting blade 506. It will be appreciated that the mechanism shown inFIGS. 5B-5C can be used with any of the cutting instruments 200, 300,400 described above. As shown, the cutting blade 506 defines a proximalyoke portion in which the distal end of the actuation shaft 504 isreceived. Each fork of the yoke portion defines a curved cam slot 566. Across-pin 568 extends through a hole formed in the distal end of theactuation shaft 504 and through each of the cam slots 566 of the cuttingblade 506. In operation, proximal translation of the actuation shaft 504relative to the body 502 causes the cross-pin 568 to slide along the camslots 566, thereby causing the blade 506 to pivot about the first andsecond side pins 522 and to be deployed through the opening. The degreeto which the actuation shaft 504 is translated proximally controls thedegree to which the cutting blade 506 protrudes from the opening. Distaltranslation of the actuation shaft 504 relative to the body 502 causesthe blade 506 to pivot in the opposite direction about the first andsecond side pins 522 and to be retracted into the cavity 520.

As shown in FIGS. 5D-5F, a cylindrical proximal portion of the body 502defines a first longitudinal slot 528 in which a first tab portion 530of the actuation shaft 504 is slidably positioned. The slot 528 has alength that is greater than the length of the tab 530, such that the tabcan slide longitudinally within the slot between a proximal position inwhich the blade 506 is fully-deployed and a distal position in which theblade is fully-retracted. The length of the slot 528 thus defines therange of diameters to which the blade 506 can be deployed and thereforethe range of tunnel diameters that can be formed by the blade. As shownin FIG. 5F, the stop ring 512 has a stepped distal-facing surface 570.Accordingly, the length of the stop ring 512 differs at each of aplurality of discrete radial positions about the circumference of thestop ring. As also shown in FIG. 5F, the stop ring 512 covers at least aproximal portion of the slot 528, such that the proximal travel limit ofthe tab 530 is defined by the stop ring. The effective length of theslot 528 can thus be changed by changing which step of the stop ring 512is aligned with the slot. The illustrated stop ring 512 has a first step572 at which the length of the stop ring is at its maximum. The lengthof the stop ring 512 is reduced at each successive step as one moves inthe direction of the arrow A1. A pair of spring clips 574 fix therotational position of the adjustment knob 548 relative to the stop ring512, such that rotation of the adjustment knob is effective to rotatethe stop ring relative to the body 502. Accordingly, rotating theadjustment knob 548 in a first direction about the longitudinal axis Laligns taller steps of the stop ring 512 with the slot 528 toeffectively reduce the length of the slot and thus decrease the maximumcutting diameter. Rotating the adjustment knob 548 in a second, oppositedirection about the longitudinal axis L aligns shorter steps of the stopring 512 with the slot 528 to effectively increase the length of theslot and thus increase the maximum cutting diameter.

In some instances, it can be easier to control the tolerances of astepped stop ring of the type used in the instrument 500 as comparedwith other types of stop rings such as the threaded stop ring of theinstrument 400. The stepped stop ring can thus provide, in someinstances, more uniform rotation and easier calibration.

The cylindrical proximal portion of the body 502 also defines upper andlower second longitudinal slots 532 in which upper and lower second tabportions 534 of the actuation shaft 504 are slidably positioned. Theactuation knob 508 is rotatably positioned over the cylindrical proximalportion of the body 502 such that a threaded interior surface of theactuation knob engages threaded surfaces of the upper and lower secondtabs 534 of the actuation shaft 504.

The actuation knob 508 is sandwiched between a proximal retaining clip514 and the disc handle 510 to maintain the actuation knob at a fixedlongitudinal position relative to the body 502. In operation, rotationof the actuation knob 508 relative to the body 502 and the handleportion 510 causes the threads of the actuation shaft 504 to ride alongthe threads of actuation knob, thus causing the actuation shaft totranslate longitudinally relative to the body. The proximal limit ofthis longitudinal translation is defined by which step of the stop ring512 is positioned over the first slot 528. The actuation knob 508 can berotated in a first direction about the longitudinal axis L to pull theactuation shaft 504 proximally and deploy the blade 506 and/or increasethe cutting diameter. The actuation knob 508 can also be rotated in asecond, opposite direction about the longitudinal axis L to push theactuation shaft 504 distally and retract the blade 506 and/or decreasethe cutting diameter.

As noted above, the position of the stop ring 512 can be adjusted byrotating the adjustment knob 548 relative to the body 502 and the dischandle 510. As shown in FIG. 5E, the adjustment knob 548 includes a pin556 that extends proximally from a proximal-facing end surface of theadjustment knob. The pin 556 can be received in any of a plurality ofholes 558 formed in the disc handle 510. Each of the holes 558 isindexed to a predetermined cutting diameter (e.g., such that movement ofthe pin 556 from one hole to an adjacent hole results in a 0.5 mmincrease or decrease in cutting diameter depending on the direction ofthe adjacency). To adjust the diameter setting, the adjustment knob 548can be urged distally to withdraw the pin 556 from the holes 558 in thedisc handle 510. The adjustment knob 548 can then be rotated to thedesired setting (which can be indicated by markings on the adjustmentknob and an indicator arrow 560 on the disc handle 510). Finally, theadjustment knob 548 can be urged proximally such that the pin 556engages one of the plurality of holes 558 formed in the disc handle 510.A bias spring 562 can be provided to urge the adjustment knob 548 in theproximal direction. When the pin 556 is seated in one of the holes 558,it prevents the adjustment knob 548 from being rotated, and ensures thatthe stop ring 5112 will not inadvertently move. This ensures that theinstrument 500 remains set to the desired diameter throughout thecutting operation. The bias spring 562 provides compression on theadjustment knob 548, keeping the pin 556 seated in the hole 558 untilthe user overcomes the spring force by pushing the adjustment knobdistally. A distal c-clip 564 can be attached to the body 502 to providea distal stop for the bias spring 562.

In an exemplary method of using the instrument 500, the instrument canbe prepared for use by a surgical technician on a “back table” beforehanding the instrument to the surgeon. This preparation can includesetting the retro-cutting diameter using the adjustment knob 548 asdescribed above and rotating the actuation handle 508 to position theblade 506 in the fully-retracted position. When the surgeon is ready toform a stepped opening, the surgeon actuates a drill to which theinstrument 500 is coupled to form the reduced diameter portion of theopening with the forward cutting tip 518. The surgeon then rotates theactuation handle 508 until further rotation is not possible, indicatingthat the blade 506 has been deployed to the pre-determined limit set bythe surgical technician using the adjustment knob 548. The surgeon thenactuates the drill to retro-cut the enlarged diameter portion of thestepped opening. Finally, the surgeon rotates the actuation handle 508to return the cutting blade 506 to the fully-retracted position andwithdraws the instrument 500 from the patient. Accordingly, the surgeonneed not be concerned with setting the instrument 500 to the desireddiameter while the instrument is in the patient. Rather, the desireddiameter is pre-set and thus the surgeon can simply turn the actuationknob 508 until the stop ring 512 is engaged by the tab 530, reliablyreaching the desired cutting diameter. In other words, the surgeon doesnot need to look at scales or calibrations when deploying the blade 506.The instrument 500 can also be used in other exemplary methods, asdescribed further below.

FIGS. 6A-6F illustrate another exemplary embodiment of a cuttinginstrument 600.

As shown, the instrument 600 generally includes an elongate body 602that extends from a proximal end 602 p to a distal end 602 d along alongitudinal axis L. The instrument 600 also includes an actuation shaft604, a cutting blade 606, an actuation knob 608, an adjustment ring 648with a stepped stop surface 670, and a forward handle 610.

The proximal end of the body 602 defines a faceted mating interface orshank 616 for coupling to the chuck of a drill (e.g., an electric orpneumatic surgical drill). The distal end of the body 602 defines asharpened tip 618 for cutting a hole in an object in an antegrade orforward direction. The tip 618 can have any of a variety of shapes orconfigurations, and can be optimized for forward cutting performance.The body 602 also includes a cavity 620 in which the cutting blade 606is pivotally mounted via a cross pin 622. The cutting blade 606 can beselectively deployed or retracted through the opening of the cavity 620.In other words, the cutting blade 606 can be positioned in a deployedconfiguration in which the blade protrudes through the opening, and aretracted configuration in which the blade does not protrude through theopening. The degree to which the blade 606 protrudes from the openingcan be adjusted to adjust the diameter of the hole that is formed whenthe instrument 600 is used in a cutting operation. The cutting blade 606can have any of a variety of shapes or configurations, and can beoptimized for retrograde cutting and/or antegrade cutting performance.

The actuation shaft 604 extends through an inner lumen of the body 602and is longitudinally-translatable relative to the body. The actuationshaft 604 can be a solid cylindrical rod, which can advantageouslyprovide additional strength and rigidity and reduced deformation duringuse. The distal end of the actuation shaft 604 can be coupled to thecutting blade 606 in any of a variety of ways. For example, as shown inFIGS. 6B-6C, a linkage assembly can be used to couple the actuationshaft 604 to the cutting blade 606. As shown, the cutting blade 606defines a proximal yoke portion in which a distal end of a link bar 676is received. The distal end of the link bar 676 is coupled to thecutting blade 606 by a first pivot pin 678. The proximal end of the linkbar 676 is received in a yoke formed in the distal end of the actuationshaft 604 and is coupled thereto by a second pivot pin 680. The link bar676 is coupled to the blade 606 at a position offset from the cross pin622, such that longitudinal translation of the link bar causes the bladeto rotate about the cross pin. In operation, proximal translation of theactuation shaft 604 relative to the body 602 pulls the link bar 676 in aproximal direction, causing the blade 606 to rotate about the cross pin622 to the retracted position. Distal translation of the actuation shaft604 relative to the body 602 pushes the link bar 676 in a distaldirection, causing the blade 606 to rotate about the cross pin 622 tothe deployed position. The degree to which the actuation shaft 604 istranslated distally controls the degree to which the cutting blade 606protrudes from the opening. A linkage of the type shown canadvantageously provide a stiffer blade mechanism with little or no playin the blade as it is deployed and used in a cutting operation. Also,the illustrated cylindrical openings through which the first and secondpivot pins 678, 680 are inserted can be easier to manufacture withprecise tolerances than elongated cam slots or other mating features.Further, in the illustrated embodiment, pressure on the blade 606 whenthe blade is used for retrograde cutting tends to urge the actuationshaft 604 proximally. This urging is resisted by the threaded engagementbetween the actuation shaft 604 and the actuation knob 608, whichprovides a solid engagement to reduce or eliminate play in the blade 606during cutting.

As shown in FIGS. 6D-6F, a cylindrical proximal portion of the body 602defines a first longitudinal slot 628 in which a first tab portion 630of the actuation shaft 604 is slidably positioned. The slot 628 has alength that is greater than the length of the tab 630, such that the tabcan slide longitudinally within the slot between a proximal position inwhich the blade 606 is fully-retracted and a distal position in whichthe blade is fully-deployed. The length of the slot 628 thus defines therange of diameters to which the blade 606 can be deployed and thereforethe range of tunnel diameters that can be formed by the blade. As shownin FIG. 6E, the adjustment ring 648 includes a proximal-facing steppedstop surface 670. Accordingly, the length of the adjustment ring 648differs at each of a plurality of discrete radial positions about thecircumference of the stop surface 670. As shown in FIG. 6F, theadjustment ring 648 covers at least a distal portion of the slot 628,such that the distal travel limit of the tab 630 is defined by the stopsurface 670. The effective length of the slot 628 can thus be changed bychanging which step of the stop surface 670 is aligned with the slot.The illustrated stop surface 670 has a first step 672 at which thelength of the adjustment ring 648 is at its maximum. The length of theadjustment ring 648 is reduced at each successive step as one moves inthe direction of the arrow A1. Rotating the adjustment ring 648 in afirst direction about the longitudinal axis L aligns taller steps of thestop surface 670 with the slot 628 to effectively reduce the length ofthe slot and thus decrease the maximum cutting diameter. Rotating theadjustment ring 648 in a second, opposite direction about thelongitudinal axis L aligns shorter steps of the stop surface 670 withthe slot 628 to effectively increase the length of the slot and thusincrease the maximum cutting diameter.

The cylindrical proximal portion of the body 602 also defines upper andlower second longitudinal slots 632 in which upper and lower second tabportions 634 of the actuation shaft 604 are slidably positioned. Theactuation knob 608 is rotatably positioned over the cylindrical proximalportion of the body 602 such that a threaded interior surface of theactuation knob engages threaded surfaces of the upper and lower secondtabs 634 of the actuation shaft 604.

The actuation knob 608 is sandwiched between a proximal retaining clip614 and a shoulder 640 of the body 602 to maintain the actuation knob ata fixed longitudinal position relative to the body. In operation,rotation of the actuation knob 608 relative to the body 602 and theforward handle portion 610 (which is pinned to the body to preventrotation of the handle portion relative to the body) causes the threadsof the actuation shaft 604 to ride along the threads of actuation knob,thus causing the actuation shaft to translate longitudinally relative tothe body. The distal limit of this longitudinal translation is definedby which step of the stop surface 670 is aligned with the first slot628. The actuation knob 608 can be rotated in a first direction aboutthe longitudinal axis L to pull the actuation shaft 604 proximally andretract the blade 606 and/or decrease the cutting diameter. Theactuation knob 608 can also be rotated in a second, opposite directionabout the longitudinal axis L to push the actuation shaft 604 distallyand deploy the blade 606 and/or increase the cutting diameter.

As noted above, the position of the stop surface 670 can be adjusted byrotating the adjustment ring 648 relative to the body 602 and theforward handle 610. As shown in FIG. 6E, the handle 610 includes a pin656 that extends proximally from a proximal-facing end surface of thehandle. The pin 656 can be received in any of a plurality of holes 658formed in the adjustment ring 648. Each of the holes 658 is indexed to apredetermined cutting diameter (e.g., such that movement of the pin 656from one hole to an adjacent hole results in a 0.5 mm increase ordecrease in cutting diameter depending on the direction of theadjacency). To adjust the diameter setting, the adjustment ring 648 canbe urged proximally to withdraw the pin 656 from the holes 658 in theadjustment ring. The adjustment ring 648 can then be rotated to thedesired setting (which can be indicated by markings on the adjustmentring and an indicator arrow 660 on the forward handle 610). Finally, theadjustment ring 648 can be urged distally such that the pin 656 engagesone of the plurality of holes 658 formed in the adjustment ring. A biasspring 662 can be provided to urge the adjustment ring 648 in the distaldirection.

In an exemplary method of using the instrument 600, the instrument canbe prepared for use by a surgical technician on a “back table” beforehanding the instrument to the surgeon. This preparation can includesetting the retro-cutting diameter using the adjustment ring 648 asdescribed above and rotating the actuation handle 608 to position theblade 606 in the fully-retracted position. When the surgeon is ready toform a stepped opening, the surgeon actuates a drill to which theinstrument 600 is coupled to form the reduced diameter portion of theopening with the forward cutting tip 618. The surgeon then rotates theactuation handle 608 until further rotation is not possible, indicatingthat the blade 606 has been deployed to the pre-determined limit set bythe surgical technician using the adjustment ring 648. The surgeon thenactuates the drill to retro-cut the enlarged diameter portion of thestepped opening. Finally, the surgeon rotates the actuation handle 608to return the cutting blade 606 to the fully-retracted position andwithdraws the instrument 600 from the patient. Accordingly, the surgeonneed not be concerned with setting the instrument 600 to the desireddiameter while the instrument is in the patient. Rather, the desireddiameter is pre-set and thus the surgeon can simply turn the actuationknob 608 until the stop 670 is engaged by the tab 630, reliably reachingthe desired cutting diameter. In other words, the surgeon does not needto look at scales or calibrations when deploying the blade 606. Theinstrument 600 can also be used in other exemplary methods, as describedfurther below.

FIGS. 7A-7G illustrate another exemplary embodiment of a cuttinginstrument 700.

As shown, the instrument 700 generally includes an elongate body 702that extends from a proximal end 702 p to a distal end 702 d along alongitudinal axis L. The instrument 700 also includes an actuation shaft704, a cutting blade 706, an actuation knob 708 with a torque limiter782, an adjustment ring 748 with a stepped stop surface 770, and aforward handle 710.

The proximal end of the body 702 defines a faceted mating interface orshank 716 for coupling to the chuck of a drill (e.g., an electric orpneumatic surgical drill). The distal end of the body 702 defines asharpened tip 718 for cutting a hole in an object in an antegrade orforward direction. The tip 718 can have any of a variety of shapes orconfigurations, and can be optimized for forward cutting performance.The body 702 also includes a cavity 720 in which the cutting blade 706is pivotally mounted via a cross pin 722. The cutting blade 706 can beselectively deployed or retracted through the opening of the cavity 720.In other words, the cutting blade 706 can be positioned in a deployedconfiguration in which the blade protrudes through the opening, and aretracted configuration in which the blade does not protrude through theopening. The degree to which the blade 706 protrudes from the openingcan be adjusted to adjust the diameter of the hole that is formed whenthe instrument 700 is used in a cutting operation. The cutting blade 706can have any of a variety of shapes or configurations, and can beoptimized for retrograde cutting and/or antegrade cutting performance.

The actuation shaft 704 extends through an inner lumen of the body 702and is longitudinally-translatable relative to the body. The actuationshaft 704 can be a solid cylindrical rod, which can advantageouslyprovide additional strength and rigidity and reduced deformation duringuse. The distal end of the actuation shaft 704 can be coupled to thecutting blade 706 in any of a variety of ways. For example, theactuation shaft 704 can have a distal end which is coupled to thecutting blade 706 by a linkage assembly as described above with respectto the instrument 600. In operation, proximal translation of theactuation shaft 704 relative to the body 702 pulls the blade 706 in aproximal direction, causing the blade to rotate about the cross pin 722to the retracted position. Distal translation of the actuation shaft 704relative to the body 702 pushes the blade 706 in a distal direction,causing the blade to rotate about the cross pin 722 to the deployedposition. The degree to which the actuation shaft 704 is translateddistally controls the degree to which the cutting blade 706 protrudesfrom the opening.

As shown in FIGS. 7C-7D and 7G, a cylindrical proximal portion of thebody 702 defines a first longitudinal slot 728 in which a first tabportion 730 of the actuation shaft 704 is slidably positioned. The slot728 has a length that is greater than the length of the tab 730, suchthat the tab can slide longitudinally within the slot between a proximalposition in which the blade 706 is fully-retracted and a distal positionin which the blade is fully-deployed. The length of the slot 728 thusdefines the range of diameters to which the blade 706 can be deployedand therefore the range of tunnel diameters that can be formed by theblade. As shown in FIG. 7G, the adjustment ring 748 includes aproximal-facing stepped stop surface 770. Accordingly, the length of theadjustment ring 748 differs at each of a plurality of discrete radialpositions about the circumference of the stop surface 770. As shown inFIG. 7G, the adjustment ring 748 covers at least a distal portion of theslot 728, such that the distal travel limit of the tab 730 is defined bythe stop surface 770. The effective length of the slot 728 can thus bechanged by changing which step of the stop surface 770 is aligned withthe slot. The illustrated stop surface 770 has a first step 772 at whichthe length of the adjustment ring 748 is at its maximum. The length ofthe adjustment ring 748 is reduced at each successive step as one movesin the direction of the arrow A1. Rotating the adjustment ring 748 in afirst direction about the longitudinal axis L aligns taller steps of thestop surface 770 with the slot 728 to effectively reduce the length ofthe slot and thus decrease the maximum cutting diameter. Rotating theadjustment ring 748 in a second, opposite direction about thelongitudinal axis L aligns shorter steps of the stop surface 770 withthe slot 728 to effectively increase the length of the slot and thusincrease the maximum cutting diameter.

The cylindrical proximal portion of the body 702 also defines upper andlower second longitudinal slots 732 in which upper and lower second tabportions 734 of the actuation shaft 704 are slidably positioned. Theactuation knob 708 is coupled to the torque limiter 782, which isrotatably positioned over the cylindrical proximal portion of the body702 such that a threaded interior surface of the torque limiter engagesthreaded surfaces of the upper and lower second tabs 734 of theactuation shaft 704.

The actuation knob 708 is sandwiched between a proximal retaining clip714 and a shoulder 740 of the body 702. In operation, rotation of theactuation knob 708 relative to the body 702 and the forward handleportion 710 (which is pinned to the body to prevent rotation of thehandle portion relative to the body) causes the threads of the actuationshaft 704 to ride along the threads of the torque limiter 782, thuscausing the actuation shaft to translate longitudinally relative to thebody. The distal limit of this longitudinal translation is defined bywhich step of the stop surface 770 is aligned with the first slot 728.The actuation knob 708 can be rotated in a first direction about thelongitudinal axis L to pull the actuation shaft 704 proximally andretract the blade 706 and/or decrease the cutting diameter. Theactuation knob 708 can also be rotated in a second, opposite directionabout the longitudinal axis L to push the actuation shaft 704 distallyand deploy the blade 706 and/or increase the cutting diameter.

As shown in FIGS. 7E-7F, the torque limiter 782 is received within aproximal cylindrical recess formed in the actuation knob 708 such that aseries of teeth 784 formed on the distal-facing surface of the torquelimiter engage a corresponding series of teeth 786 formed in the recessof the actuation knob. As the actuation knob 708 is rotated and thecutting blade 706 approaches or reaches the fully-deployed position, thefirst tab 730 on the actuation shaft 704 engages the stop surface 770,preventing further rotation of the torque limiter 782. If the usercontinues to apply torque to the actuation knob 708, the teeth 784, 786temporarily disengage and the actuation knob 708 slips relative to thetorque limiter 782. This slipping can generate tactile and/or audiblefeedback to the user indicating that the blade has reached thefully-deployed position. In addition, the slipping can prevent damage tothe instrument 700 that might otherwise occur if excessive torque isapplied after the blade reaches the fully-deployed position. Thethreshold torque at which the teeth 784, 786 disengage can be set to anydesired value by varying the spring force of the bias spring 762 and/orthe shape, ramp angle, or other properties of the teeth. In someembodiments, the instrument 700 can provide a similar torque limitingfunction as the blade 706 approaches or reaches the fully-retractedposition.

As noted above, the position of the stop surface 770 can be adjusted byrotating the adjustment ring 748 relative to the body 702 and theforward handle 710. As shown in FIGS. 7D-7E, the handle 710 includes aplurality of protrusions 756 (four in the illustrated embodiment) thatextend proximally from a proximal-facing end surface of the handle. Theprotrusions 756 can be received in any of a plurality of holes ordetents 758 formed in the adjustment ring 748. Each of the holes 758 isindexed to a predetermined cutting diameter (e.g., such that movement ofthe protrusions 756 from one set of holes to an adjacent set of holesresults in a 0.5 mm increase or decrease in cutting diameter dependingon the direction of the adjacency). To adjust the diameter setting, theadjustment ring 748 is rotated to the desired setting (which can beindicated by markings on the adjustment ring and an indicator arrow 760on the forward handle 710). As the adjustment ring 748 is rotated, theopenings 758 formed therein cam over the dome-shaped protrusions 756,deflecting the adjustment ring 748 proximally against the resistance ofthe bias spring 762. When the protrusions 756 fall into an adjacent setof openings 758 in the adjustment ring 748, the adjustment ring springsdistally under the force of the bias spring 762, providing tactilefeedback to the user that the next setting has been reached.

In an exemplary method of using the instrument 700, the instrument canbe prepared for use by a surgical technician on a “back table” beforehanding the instrument to the surgeon. This preparation can includesetting the retro-cutting diameter using the adjustment ring 748 asdescribed above and rotating the actuation handle 708 to position theblade 706 in the fully-retracted position. When the surgeon is ready toform a stepped opening, the surgeon actuates a drill to which theinstrument 700 is coupled to form the reduced diameter portion of theopening with the forward cutting tip 718. The surgeon then rotates theactuation handle 708 until the actuation handle 708 slips relative tothe torque limiter 782, which provides tactile and/or audible feedbackto the surgeon to indicate that the blade 706 has been deployed to thepre-determined limit set by the surgical technician using the adjustmentring 748. The surgeon then actuates the drill to retro-cut the enlargeddiameter portion of the stepped opening. Finally, the surgeon rotatesthe actuation handle 708 to return the cutting blade 706 to thefully-retracted position and withdraws the instrument 700 from thepatient. Accordingly, the surgeon need not be concerned with setting theinstrument 700 to the desired diameter while the instrument is in thepatient. Rather, the desired diameter is pre-set and thus the surgeoncan simply turn the actuation knob 708 until the stop surface 770 isengaged by the tab 730, reliably reaching the desired cutting diameter.In other words, the surgeon does not need to look at scales orcalibrations when deploying the blade 706. The instrument 700 can alsobe used in other exemplary methods, as described further below.

The instruments disclosed herein can be constructed from any of avariety of known materials. Exemplary materials include those which aresuitable for use in surgical applications, including metals such asstainless steel, polymers such as PEEK, ceramics, and so forth.

The instruments disclosed herein can be adjustable to any of a varietyof diameters. In some embodiments, the instrument body has a diameter ofabout 3.5 mm with the blade completely retracted. In some embodiments,the blade can be deployed to a diameter in the range of about 3.5 mm toabout 24 mm, in the range of about 3.5 mm to about 12 mm, in the rangeof about 6 mm to about 12 mm, in the range of about 6 mm to about 8 mm,in the range of about 8 mm to about 10 mm, or in the range of about 10mm to about 12 mm. The instruments disclosed herein can be “analog” suchthat any diameter within a particular operating range can be selected bythe user. The instruments disclosed herein can also be “digital” suchthat a finite plurality of discrete diameter settings are available tothe user. These finite steps can be arranged in predetermined increments(e.g., quarter millimeter increments, half millimeter increments, onemillimeter increments, and/or two millimeter increments).

As the above-described instruments are merely exemplary embodiments, itwill be appreciated that the features of any particular instrument canbe incorporated into any other instrument without departing from thescope of the present disclosure.

The opening through which the blade is deployed can be formed in any ofa variety of locations along the length of the body. In someembodiments, the opening is formed just proximal to the distal tip ofthe body, for example, starting about 4 mm from the terminal distal endof the body and extending about 11 mm to a point that is about 15 mmfrom the terminal distal end of the body. The opening can also be formedat a greater distance from the distal tip of the body, for example at amidpoint of the body. As detailed below, this configuration canadvantageously facilitate certain methods in which antegrade reaming ofa femoral tunnel using an anteromedial approach is performed.

Methods

The instruments disclosed herein can be used in any of a variety ofsurgical methods, which can be performed on humans or animals. Theinstruments disclosed herein can also be used in non-surgical methods,for example in manufacturing or woodworking methods or in any othermethods in which retrograde cutting, antegrade cutting, drilling,stepped tunnel formation, or other steps facilitated by said instrumentsare desired. It will be appreciated that the instruments disclosedherein can be used for both antegrade cutting and retrograde cutting.

In the methods described below, reference is made to the instrument 700described above. It will be appreciated, however, that any of the otherinstruments disclosed or contemplated herein can be used to carry outthese methods, with the methods being modified accordingly if necessary,as will be readily understood by those skilled in the art.

FIGS. 8A-8F illustrate an exemplary method of using a cutting instrument700 to form a stepped bone tunnel in a femur 800. The method can employa lateral approach as shown, or any other approach including a medialapproach, an anterior approach, a posterior approach, an anteromedialapproach, an anterolateral approach, a posteromedial approach, aposterolateral approach, etc. In addition, while a femur is used as anexemplary bone in which the tunnel is formed, it will be appreciatedthat the method can be used to form a tunnel in any bone or otherobject.

As shown in FIG. 8A, the distal drilling tip 718 of the instrument 700can be targeted to a point on the exterior of the patient's femur 800via an arthroscopic portal or an open skin incision. Prior to targetingthe instrument 700 to the patient's femur 800, or at any other desiredtime, the actuation knob 708 of the instrument can be rotated in a firstdirection to fully-retract the cutting blade 706 and the adjustment ring748 can be rotated to set the desired cutting diameter limit. Thesesteps can be performed by a surgical technician on a back table of theoperating room, before handing the instrument 700 to the surgeon. Asshown in FIG. 8B, the surgeon can actuate a drill to which the cuttinginstrument 700 is coupled to form a first opening 802 in the femur 800by antegrade cutting with the distal tip 718 of the cutting instrument.The first opening 802 has a diameter D1 which is substantially equal tothe outside diameter of the body 702 of the cutting instrument 700. Thefirst opening 802 can be formed to a desired depth, for example asindicated by depth markings and/or a depth stop on the exterior of thebody 702 of the cutting instrument 700. As shown in FIG. 8C, with thedistal end of the instrument 700 in the joint space, the surgeon canrotate the actuation knob 708 in a second, opposite direction until thecutting blade 706 has been deployed to the preset cutting diameterlimit. As shown in FIG. 8D, the surgeon can then actuate the drill toform a second opening 804 in the femur 800 by retrograde cutting withthe deployed cutting blade 706 of the instrument 700. The second opening804 has a diameter D2 which is greater than the diameter D1 and which issubstantially equal to the pre-set limit diameter. When the secondopening 804 reaches the desired depth, which can be indicated to thesurgeon by depth markings and/or a depth stop on the exterior of thebody 702 of the cutting instrument 700, the actuation knob 708 can berotated in the first direction to fully-retract the cutting blade 706into the body, as shown in FIG. 8E. The cutting instrument 700 can thenbe withdrawn from the patient, as shown in FIG. 8F, leaving a steppedbone tunnel or socket in which a soft tissue graft can be mounted (e.g.,to complete an ACL reconstruction or other procedure).

FIGS. 9A-9F illustrate an exemplary method of using a cutting instrument700 to form a femoral socket using a trans-tibial approach. It will beappreciated that the method can use any of a variety of otherapproaches, and that the method can be used to form a socket in anyother bone or object.

As shown in FIG. 9A, the distal drilling tip 718 of the instrument 700can be targeted to a point on the exterior of the patient's tibia 906via an arthroscopic portal or an open skin incision. Prior to targetingthe instrument 700 to the patient's tibia 906, or at any other desiredtime, the actuation knob 708 of the instrument can be rotated in a firstdirection to fully-retract the cutting blade 706 and the adjustment ring748 can be rotated to set the desired cutting diameter limit. Thesesteps can be performed by a surgical technician on a back table of theoperating room, before handing the instrument to the surgeon. As shownin FIG. 9B, the surgeon can actuate a drill to which the cuttinginstrument 700 is coupled to form a first opening 908 in the tibia 906by antegrade cutting with the distal tip 718 of the cutting instrument.The first opening 908 has a diameter D1 which is substantially equal tothe outside diameter of the body 702 of the cutting instrument 700. Thefirst opening 908 can be formed to a desired depth, for example asindicated by depth markings and/or a depth stop on the exterior of thebody 702 of the cutting instrument 700. As shown in FIG. 9C, with thedistal end of the instrument 700 in the joint space, the surgeon canrotate the actuation knob 708 in a second, opposite direction until thecutting blade 706 has been deployed to the preset cutting diameterlimit. As shown in FIG. 9D, the surgeon can then actuate the drill toform a second opening 910 in the femur 900 by antegrade cutting with thedeployed cutting blade 706 of the instrument 700. The second opening 910has a diameter D2 which is greater than the diameter D1 and which issubstantially equal to the pre-set limit diameter. When the secondopening 910 reaches the desired depth, which can be indicated to thesurgeon by depth markings and/or a depth stop on the exterior of thebody 702 of the cutting instrument 700, the actuation knob 708 can berotated in the first direction to fully-retract the cutting blade 706into the body, as shown in FIG. 9E. The cutting instrument 700 can thenbe withdrawn from the patient, as shown in FIG. 9F, leaving a femoralsocket 910 in which a soft tissue graft can be mounted (e.g., tocomplete an ACL reconstruction or other procedure).

FIGS. 10A-10F illustrate another exemplary method of using a cuttinginstrument 700 to form a femoral socket using an anteromedial approach.It will be appreciated that the method can use any of a variety ofapproaches, and that the method can be used to form a socket in anyother bone or object.

As shown in FIG. 10A, the distal drilling tip 718 of the instrument 700can be targeted to a point within the femoral notch on the lateralcondyle of the patient's femur 1000 via an arthroscopic portal or anopen skin incision. In some embodiments, the instrument 700 can be atleast partially inserted through an anteromedial portal, which can beformed, for example, about 1 cm medial to the patellar tendon and justdistal to the inferior pole of the patella. Prior to targeting theinstrument 700 to the patient's femur 1000, or at any other desiredtime, the actuation knob 708 of the instrument 700 can be rotated in afirst direction to fully-retract the cutting blade 706 and theadjustment ring 748 can be rotated to set the desired cutting diameterlimit. These steps can be performed by a surgical technician on a backtable of the operating room, before handing the instrument 700 to thesurgeon. As shown in FIG. 10B, the surgeon can actuate a drill to whichthe cutting instrument 700 is coupled to form a first opening 1002through the lateral condyle of the femur by antegrade cutting with thedistal tip 718 of the cutting instrument. There is little risk ofdamaging the cartilage on the medial condyle when forming the firstopening 1002, as the outside diameter of the instrument 700 isrelatively small as it passes the medial condyle. The first opening 1002has a diameter D1 which is substantially equal to the outside diameterof the body 702 of the cutting instrument 700. The first opening 1002can be formed to a desired depth, for example as indicated by depthmarkings and/or a depth stop on the exterior of the body 702 of thecutting instrument 700. As shown in FIG. 10C, with the midpoint or asubstantially middle section of the instrument 700 in the joint space,the surgeon can rotate the actuation knob 708 in a second, oppositedirection until the cutting blade 706 has been deployed to the presetcutting diameter limit. As shown in FIG. 10D, the surgeon can thenactuate the drill to enlarge a portion of the first opening 1002 byforming a second opening 1004 by antegrade cutting with the deployedcutting blade 706 of the instrument 700. Again, there is little risk ofdamaging the cartilage on the medial condyle when forming the secondopening 1004, as the outside diameter of the portion of the instrument700 adjacent to the medial condyle is relatively small. The secondopening 1004 has a diameter D2 which is greater than the diameter D1 andwhich is substantially equal to the pre-set limit diameter. When thesecond opening 1004 reaches the desired depth, which can be indicated tothe surgeon by depth markings and/or a depth stop on the exterior of thebody 702 of the cutting instrument 700, the actuation knob 708 can berotated in the first direction to fully-retract the cutting blade 706into the body, as shown in FIG. 10E. The cutting instrument 700 can thenbe withdrawn from the patient, as shown in FIG. 10F, leaving a femoralsocket 1004 in which a soft tissue graft can be mounted (e.g., tocomplete an ACL reconstruction or other procedure).

It will be appreciated that the instruments disclosed herein can be usedin any of a variety of other methods.

The instruments disclosed herein can be designed to be disposed of aftera single use, or they can be designed to be used multiple times. Ineither case, however, the instrument can be reconditioned for reuseafter at least one use. Reconditioning can include any combination ofthe steps of disassembly of the instrument, followed by cleaning orreplacement of particular pieces, and subsequent reassembly. Inparticular, the instrument can be disassembled, and any number of theparticular pieces or parts of the instrument can be selectively replacedor removed in any combination. Upon cleaning and/or replacement ofparticular parts, the instrument can be reassembled for subsequent useeither at a reconditioning facility, or by a surgical team immediatelyprior to a surgical procedure. Those skilled in the art will appreciatethat reconditioning of a instrument can utilize a variety of techniquesfor disassembly, cleaning/replacement, and reassembly. Use of suchtechniques, and the resulting reconditioned instrument, are all withinthe scope of the present application.

Preferably, the invention described herein will be processed beforesurgery. First, a new or used instrument is obtained and if necessarycleaned. The instrument can then be sterilized. In one sterilizationtechnique, the instrument is placed in a closed and sealed container,such as a plastic or TYVEK bag. The container and instrument are thenplaced in a field of radiation that can penetrate the container, such asgamma radiation, x-rays, or high-energy electrons. The radiation killsbacteria on the instrument and in the container. The sterilizedinstrument can then be stored in the sterile container. The sealedcontainer keeps the instrument sterile until it is opened in the medicalfacility.

It is preferred that the instrument is sterilized. This can be done byany number of ways known to those skilled in the art including beta orgamma radiation, ethylene oxide, steam, and a liquid bath (e.g., coldsoak).

Although the invention has been described by reference to specificembodiments, it should be understood that numerous changes may be madewithin the spirit and scope of the inventive concepts described.Accordingly, it is intended that the invention not be limited to thedescribed embodiments, but that it have the full scope defined by thelanguage of the following claims.

The invention claimed is:
 1. A cutting instrument, comprising: anelongate body having proximal and distal ends, the distal end defining adrilling tip; a cutting blade pivotally disposed within a cavity formedin the elongate body such that the cutting blade is positionable in aretracted position in which the cutting blade does not protrude from theelongate body and one or more deployed positions in which the cuttingblade protrudes from the elongate body; an actuation shaft extendingthrough the elongate body and having a distal end coupled to the cuttingblade such that longitudinal translation of the actuation shaft relativeto the elongate body is effective to move the cutting blade between theretracted position and the one or more deployed positions; an actuationknob coupled to the actuation shaft such that rotation of the actuationknob about a longitudinal axis of the elongate body is effective tolongitudinally translate the actuation shaft relative to the elongatebody; and an adjustment element having a ring with a stepped stopsurface formed thereon, the stepped stop surface having a plurality ofsteps, and the adjustment element being configured to limit the degreeto which the actuation shaft can be longitudinally translated relativeto the elongate body based on which step of the plurality of steps isengaged by the actuation shaft.
 2. The instrument of claim 1, whereinthe cavity in which the cutting blade is disposed is spaced a distanceapart from the distal end of the elongate body.
 3. The instrument ofclaim 1, wherein the actuation knob is coupled to the actuation shaft bya threaded interface.
 4. The instrument of claim 1, wherein theactuation shaft includes a first tab that extends through a first slotin the elongate body.
 5. The instrument of claim 4, wherein theadjustment element is disposed over at least a portion of the first slotto limit the degree to which the first tab can slide within the firstslot.
 6. The instrument of claim 1, wherein rotation of the adjustmentelement about the longitudinal axis of the elongate body is effective tochange which step of the plurality of steps is engaged by the actuationshaft to limit the longitudinal translation of the actuation shaftrelative to the elongate body.
 7. The instrument of claim 1, furthercomprising a fixed handle portion having a plurality of protrusionsformed thereon configured to be received within a plurality of detentsor openings formed in a distal-facing surface of the adjustment element.8. The instrument of claim 7, further comprising a bias springconfigured to urge the adjustment element into engagement with the fixedhandle portion.
 9. The instrument of claim 1, wherein the actuation knobincludes a torque limiter configured to limit the amount of torque whichcan be applied in rotating the actuation knob and configured to providetactile feedback to a user when the cutting blade has reached a desiredposition.
 10. The instrument of claim 1, wherein the distal end of theactuation shaft is coupled to the cutting blade by a linkage mechanism.11. The instrument of claim 10, wherein the linkage mechanism comprisesa link bar having a proximal end coupled to a yoke of the actuationshaft by a first cross pin and a distal end coupled to a yoke of thecutting blade by a second cross pin.
 12. The instrument of claim 1,wherein proximal translation of the actuation shaft relative to theelongate body is effective to rotate the cutting blade about a pivot pinto deploy the cutting blade into the cavity and wherein distaltranslation of the actuation shaft relative to the elongate body iseffective to rotate the cutting blade about the pivot pin to retract thecutting blade from the cavity.
 13. A method of cutting bone, comprising:drilling a first opening in the bone having a first diameter using adistal tip of a cutting instrument, a cutting blade of the cuttinginstrument being retracted into a body of the cutting instrument duringsaid drilling; setting a cutting blade deployment diameter to one of aplurality of a diameter settings of the cutting instrument, the cuttingblade being in one of a plurality of fully-deployed positions at each ofthe plurality of diameter settings, with the cutting blade beingconfigured to cut an opening of a predetermined diameter at each of theplurality of fully-deployed positions, the predetermined diameter beingdifferent for different fully-deployed positions of the plurality of thefully -deployed positions: after setting the cutting blade deploymentdiameter, deploying the cutting blade to the fully-deployed position ofthe plurality of fully-deployed positions that is associated with theset cutting blade deployment diameter such that the cutting blade atleast partially protrudes from the body of the cutting instrument; andafter deploying the cutting blade, cutting a second opening in the bonehaving a second diameter which is larger than the first diameter usingthe cutting blade of the cutting instrument.
 14. The method of claim 13,wherein the first and second openings are contiguous with one anothersuch that the first and second openings define a stepped bone tunnel.15. The method of claim 13, wherein the first opening is drilled in anantegrade direction and the second opening is cut in a retrogradedirection.
 16. The method of claim 13, wherein the first opening isdrilled in an antegrade direction and the second opening is cut in anantegrade direction.
 17. The method of claim 16, wherein the firstopening is formed in a tibia and the second opening is formed in afemur.
 18. The method of claim 16, wherein the first opening is formedin a medial portion of a femur and the second opening is formed in alateral portion of the femur.
 19. The method of claim 13, furthercomprising, after cutting the second opening, retracting the cuttingblade into the body of the cutting instrument and withdrawing thecutting instrument through the first opening.
 20. A cutting instrument,comprising: a handle having a plurality of protrusions formed thereon;an elongate body extending distally from the handle, the elongate bodyhaving proximal and distal ends, the distal end defining a drilling tip;a cutting blade pivotally disposed within a cavity formed in theelongate body such that the cutting blade is positionable in a retractedposition in which the cutting blade does not protrude from the elongatebody and one or more deployed positions in which the cutting bladeprotrudes from the elongate body; an actuation shaft extending throughthe elongate body and having a distal end coupled to the cutting bladesuch that longitudinal translation of the actuation shaft relative tothe elongate body is effective to move the cutting blade between theretracted position and the one or more deployed positions; an actuationknob coupled to the actuation shaft such that rotation of the actuationknob about a longitudinal axis of the elongate body is effective tolongitudinally translate the actuation shaft relative to the elongatebody; and an adjustment element having a plurality of detents oropenings formed on a surface thereof, the plurality of detents oropenings being configured to receive the plurality of protrusions of thehandle to limit the degree to which the actuation shaft can belongitudinally translated relative to the elongate body based on whichone or more protrusions of the plurality of protrusions are received bywhich one or more detents or openings of the plurality of detents oropenings.
 21. The instrument of claim 20, wherein the cavity in whichthe cutting blade is disposed is spaced a distance apart from the distalend of the elongate body.
 22. The instrument of claim 20, wherein theadjustment element comprises a ring with a stepped stop surface having aplurality of steps formed thereon, and wherein rotation of theadjustment element about the longitudinal axis of the elongate body iseffective to change which step of the plurality of steps is engaged bythe actuation shaft to limit the longitudinal translation of theactuation shaft relative to the elongate body.
 23. The instrument ofclaim 20, further comprising a bias spring configured to urge theadjustment element into engagement with the handle.
 24. The instrumentof claim 20, wherein the actuation knob includes a torque limiterconfigured to limit the amount of torque which can be applied inrotating the actuation knob and configured to provide tactile feedbackto a user when the cutting blade has reached a desired position.
 25. Theinstrument of claim 20, wherein proximal translation of the actuationshaft relative to the elongate body is effective to rotate the cuttingblade about a pivot pin to deploy the cutting blade into the cavity andwherein distal translation of the actuation shaft relative to theelongate body is effective to rotate the cutting blade about the pivotpin to retract the cutting blade from the cavity.
 26. The instrument ofclaim 20, further comprising a linkage mechanism that includes a linkbar with a proximal end that is coupled to a yoke of the actuation shaftand a distal end that is coupled to a yoke of the cutting blade.
 27. Acutting instrument, comprising: an elongate body having proximal anddistal ends, the distal end defining a drilling tip; a cutting bladepivotally disposed within a cavity formed in the elongate body such thatthe cutting blade is positionable in a retracted position in which thecutting blade does not protrude from the elongate body and one or moredeployed positions in which the cutting blade protrudes from theelongate body; an actuation shaft extending through the elongate bodyand having a distal end coupled to the cutting blade such thatlongitudinal translation of the actuation shaft relative to the elongatebody is effective to move the cutting blade between the retractedposition and the one or more deployed positions; an actuation knobcoupled to the actuation shaft such that rotation of the actuation knobabout a longitudinal axis of the elongate body is effective tolongitudinally translate the actuation shaft relative to the elongatebody; an adjustment element configured to limit the degree to which theactuation shaft can be longitudinally translated relative to theelongate body; and a linkage mechanism that includes a link bar with aproximal end that is coupled to a yoke of the actuation shaft and adistal end that is coupled to a yoke of the cutting blade.
 28. Theinstrument of claim 27, wherein the cavity in which the cutting blade isdisposed is spaced a distance apart from the distal end of the elongatebody.
 29. The instrument of claim 27, wherein the actuation knobincludes a torque limiter configured to limit the amount of torque whichcan be applied in rotating the actuation knob and configured to providetactile feedback to a user when the cutting blade has reached a desiredposition.
 30. The instrument of claim 27, wherein the adjustment elementcomprises a ring with a stepped stop surface having a plurality of stepsformed thereon, and wherein rotation of the adjustment element about thelongitudinal axis of the elongate body is effective to change which stepof the plurality of steps is engaged by the actuation shaft to limit thelongitudinal translation of the actuation shaft relative to the elongatebody.
 31. The instrument of claim 27, wherein proximal translation ofthe actuation shaft relative to the elongate body is effective to rotatethe cutting blade about a pivot pin to deploy the cutting blade into thecavity and wherein distal translation of the actuation shaft relative tothe elongate body is effective to rotate the cutting blade about thepivot pin to retract the cutting blade from the cavity.